Many casualties on the battlefield result when medical or other rescue personnel attempt to treat or rescue a downed soldier. Also, an injured individual may be located where it is dangerous to send civilian rescue workers or other emergency first responders. It may be desirable to obtain information about the victim without exposing medical personnel to enemy fire or an otherwise hazardous environment.
Attempts to detect an individual's presence and movement with hand-held radar systems that measure the backscatter of the radar signal have been made. For example, a “Radar Flashlight” was developed by Georgia Tech Research Institute, and personnel detectors have been developed by L-3 Cyterra Inc. However, these employ single-point radar, and they may not be able to distinguish the vital signs of two victims in close proximity to each other. Also, these systems may require highly precise orientation during measurement and the radar may be unable to penetrate body armor and/or wet clothing of a victim in order to sense the victim's respiration or heart rate.